1. Field of the Invention
The present invention relates to a profile measuring instrument, an adjusting method for a profile measuring instrument and a profile measuring method. In particular, the present invention relates to a technique for continuously performing so-called roundness measurement and profile measurement.
2. Description of Related Art
Typically, a complicatedly designed product such as an aspheric lens is required to be of high precision and thus a surface profile thereof is necessarily measured with a high accuracy.
In order to measure such a product (i.e., a workpiece), a linear scanning measurement is typically performed using a linearly movable profile measuring instrument to measure a profile along a scanning axis (see Patent Literature 1: JP-A-2010-164532).
In order to measure a workpiece in the form of a revolution solid such as an aspheric lens, a rotary scanning measurement is typically performed using a profile measuring instrument or roundness measuring instrument provided with a turntable to measure a roundness of the workpiece around its center axis, i.e., a profile variation of a surface of the workpiece (see Patent Literature 2: JP-A-2010-185804 or Patent Literature 3: JP-A-2011-208994).
As described above, a workpiece in the form of a revolution solid such as an aspheric lens is subjected to both the rotary scanning measurement and the linear scanning measurement.
Typically, a roundness measuring instrument provided with a turntable is used for the rotary scanning measurement and a linearly movable profile measuring instrument is used for the linear scanning measurement.
In other words, one workpiece is necessarily measured using two different measuring instruments (i.e., the roundness measuring instrument and the profile measuring instrument) and thus the workpiece has to be positionally adjusted each time when being mounted on one of the measuring instruments.
For the rotary scanning measurement, it is necessary to adjust a deviation (eccentricity) and an inclination between a rotary axis of the turntable of the roundness measuring instrument and a center axis of the workpiece. Accordingly, prior to an actual rotary scanning measurement, a preliminary measurement has to be repeated to eliminate the eccentricity or the inclination (i.e., centering). Incidentally, the adjustment of eccentricity and the adjustment of inclination are often referred to as centering and leveling, respectively. However, the meaning of a term “centering” hereinbelow includes the centering and the leveling in the narrow sense.
Using the profile measuring instrument, the linear scanning measurement is frequently performed along a diameter of the workpiece. Accordingly, prior to an actual linear scanning measurement, it is necessary to align the scanning axis with the diameter of the workpiece (i.e., an axis passing through the center axis of the workpiece) to eliminate the inclination (i.e., aligning). Specifically, a preliminary measurement is typically repeated to eliminate the deviation between these axes or to eliminate the inclination. Incidentally, the adjustment for eliminating the deviation between the axes and the adjustment for eliminating the inclination are often referred to as aligning and leveling, respectively. However, the meaning of a term “aligning” hereinbelow includes the aligning and the leveling in the narrow sense.
Since one workpiece has to be sequentially set on the roundness measuring instrument and the profile measuring instrument to be measured as described above, the annoying preliminary measurement has to be repeated to adjust the position of the workpiece on not only the roundness measuring instrument but also the profile measuring instrument, resulting in hindrance to improvement in operating efficiency.